The invention relates to a bobbin creel which is supported on a holder so as to be pivotable by means of a four-bar linkage arranged on the machine frame of a textile machine, wherein the holder forms the stationary member of the four-bar linkage, and which is pivotable from a lower loading position into an upper operating position by means of a pneumatic cylinder connected with one end to the holder and with the other end to one of the movable four-bar linkage members.
The four-bar linkage, by definition, is comprised of four members connected to one another by four joints of which one member is stationarily mounted while the other three members, as a function of the selected dimensions of the individual members, are capable of carrying out the required rotary or swinging motions.
In a bobbin creel disclosed in FR 2 794 136 A1, a pneumatic cylinder is provided which is loaded at one end by compressed air. In order to assist the upward pivoting of the bobbin creel, provided with at least one feed, into the upper operating position, the pneumatic cylinder is loaded or supplied with compressed air such that the piston rod is moved out of the cylinder. Moreover, a spring is provided which is connected with one end to the holder and with the other end to that member of the four-bar linkage positioned opposite this holder, which spring is apparently provided in order to assist the work of the pneumatic cylinder during the upward pivoting action, on the one hand, and to secure the bobbin creel in the upper operating position, on the other hand. The downward pivoting of the bobbin creel into the lower loading position is realized exclusively by hand, in particular, against the force of the last mentioned securing spring as well as against the force of the compressed air cushion that is present in the cylinder chamber loadable with compressed air; the compressed air cushion is relieved during the downward movement by a venting bore.
The invention has the object to improve a bobbin creel in such a way that the manual operation is simplified or facilitated even during the downward pivoting action of the bobbin creel.
As a solution to this object, the pneumatic cylinder is a pneumatic cylinder which can be loaded from both ends with compressed air and comprises two pressure chambers which are separated from one another by the piston of the pneumatic cylinder such that, for pivoting the bobbin creel into the lower position, the pneumatic cylinder can be loaded with compressed air for retracting the piston rod or the piston into the cylinder chamber.
While in the known bobbin creel a first end of the pneumatic cylinder engages a member of the four-bar linkage that is directly connected to the holder, i.e., the stationary member of the four-bar linkage, and particularly engages a lifter mounted on this pivotable member, according to a further embodiment of the invention it is provided that the pneumatic cylinder with its first end is pivotably connected to the four-bar linkage member opposite the stationary holder so that the space needed for the entire system is reduced.
According to a further embodiment of the invention, a pneumatic spring is pivotably connected with both ends to the four-bar linkage and, when pivoting the bobbin creel into the loading position, is tensioned; the energy stored in this way is released for assisting the pneumatic cylinder, on the one hand, and for assisting manual actuation, on the other hand, when pivoting the bobbin creel upwardly.
As a function of the weight of the bobbin creel loaded with one or several feed bobbins, one pneumatic cylinder or two parallel positioned pneumatic cylinders can be provided according to the invention. In the case of two pneumatic cylinders, the pneumatic spring is preferably arranged centrally between the pneumatic cylinders.
Such a system provided with two pneumatic cylinders is particularly advantageous when the bobbin creel according to the invention has several adjacently positioned receiving members for placing feed bobbins thereon such that this bobbin creel is mounted substantially centrally between two work locations to which the threads or yarns removed from the feed bobbins are to be supplied.
According to a further embodiment of the invention, the bobbin creel according to the invention is preferably controlled by means of an actuating valve wherein the valve system comprises two 3/2 port directional control valves arranged immediately upstream of the pneumatic cylinder as well as two check valves which are positioned individually in branch lines connecting one of the relay valves with one of the two 3/2 port directional control valves, wherein a control line extending to the other one of the two 3/2 port directional control valves is connected to the branch line, respectively, wherein by means of the control line the two 3/2 port directional control valves can be moved between their compressed air through positions and their pressure relief positions such that a) for relay valves that are not actuated the 3/2 port directional control valves are in their compressed air through positions while the relay valves are in a position venting the branch lines, while b) upon actuation of one of the two relay valves, respectively, it assumes a compressed air through position relative to the branch line connected thereto.